Can a 22 years old with disability immigrate with his parents?

Yes, but the parents need to prove: their child 22 years of age or older, have depended substantially on the financial support of the parent since before the age of 22 and be unable to support themselves financially due to a physical or mental condition (it is the financial dependency that must have been ongoing since before the age of 22. It is not necessary for the physical or mental condition to have existed before the age of 22.)